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From: Matt Fleming <matt@console-pimps.org>
To: Jan Beulich <jbeulich@novell.com>
Cc: linux-kernel@vger.kernel.org, fenghua.yu@intel.com,
	tony.luck@intel.com, hpa@linux.intel.com, mjg@redhat.com,
	a.zummo@towertech.it
Subject: Re: [PATCH] x86, efi: Don't recursively acquire rtc_lock
Date: Thu, 04 Aug 2011 10:33:36 +0100	[thread overview]
Message-ID: <1312450416.10579.70.camel@mfleming-mobl1.ger.corp.intel.com> (raw)
In-Reply-To: <4E3A17BD0200007800073FC5@nat28.tlf.novell.com>

On Thu, 2011-08-04 at 03:53 +0100, Jan Beulich wrote:
> 
> Seems the wrong approach to me: The call happening with the lock held
> is the wrong part imo, and hence the fix ought to be to drop the lock
> there.

But what about other platforms that provide a get_wallclock()
implementation such as the kvm or xen code? If we called get_wallclock()
without rtc_lock held we'd be requiring everyone to lock it in their
clock code, which is unnecessary work and increases the amount of code
that touches rtc_lock (not to mention spreading it across several
files).

I think it's much better to do the locking as high up the callstack as
possible and preferably in as few places as possible.

-- 
Matt Fleming, Intel Open Source Technology Center


  parent reply	other threads:[~2011-08-04  9:33 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-04  2:53 Jan Beulich
2011-08-04  3:04 ` Matthew Garrett
2011-08-04  9:33 ` Matt Fleming [this message]
  -- strict thread matches above, loose matches on Subject: below --
2011-08-05 17:04 Jan Beulich
2011-08-08 13:40 ` Matt Fleming
2011-08-08 14:07   ` Jan Beulich
2011-08-10  9:03     ` Ingo Molnar
2011-08-10  9:36       ` Jan Beulich
2011-08-10  9:51         ` Ingo Molnar
2011-08-10 13:12           ` Jan Beulich
2011-08-15 18:18             ` Matt Fleming
2011-08-16  6:22               ` Jan Beulich
2011-08-16  9:14                 ` Matt Fleming
2011-08-30 15:45                   ` Matthew Garrett
2011-08-30 16:07                     ` Matt Fleming
2011-08-30 18:27                       ` H. Peter Anvin
2011-08-10 14:55           ` Jan Beulich
2011-08-08 14:18   ` Avi Kivity
2011-08-05 17:02 Jan Beulich
2011-08-03 21:04 Matt Fleming
2011-08-03 23:10 ` Tony Luck
2011-08-03 23:12 ` H. Peter Anvin
2011-08-04 10:22 ` john stultz
2011-08-04 10:36   ` Matt Fleming
2011-08-04 11:36   ` Matthew Garrett

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